Fire hazard in transportation infrastructure: Review,assessment, and mitigation strategies

This paper reviews the fire problem in critical transportation infrastructures such as bridges and tunnels. The magnitude of the fire problem is illustrated, and the recent increase in fire problems in bridges and tunnels is highlighted. Recent research undertaken to address fire problems in transportation structures is reviewed, as well as critical factors governing the performance of those structures. Furthermore, key strategies recommended for mitigating fire hazards in bridges and tunnels are presented, and their applicability to practical situations is demonstrated through a practical case study. Furthermore, research needs and emerging trends for enhancing the “state-of-the-art” in this area are discussed.     

用户身份管理策略研究

In recent years there has been a fast grow of various electronic services.Each service requires specif-ic credentials for authenticating and authorizing user ac-cess or specific subset of user's personal information for transactions the service offers.Such a situation causes problems with remembering multiple,service-specific authentication data,with controlling user's personal data spread across different services-problems with managing user's identities.This paper is an overview on Identity Management(IdM...     

Biogenic amines in Iranian white brine cheese: modelling and optimisation of processing factors

The simultaneous effects of processing factors such as ripening time (25–75 days), ripening temperature (4–14 °C) and brine concentration (10–13%) on biogenic amines content, proteolysis and sensory score of Iranian white brine cheese were studied, in 12 cheeses. Response surface methodology (RSM) was used to minimise biogenic amines content. At low level of ripening time, biogenic amines content decreased with increasing levels of brine concentration but at high level of ripening time, brine concentration had inverse effect. Ripening time showed quadratic effect on biogenic amines content. Based on biogenic amines content and sensory score, the optimum conditions were 13% brine and ripening at 9–14 °C for 43–65 days.     

Effect of microgravity on grain coarsening during liquid phase sintering in the Fe–Cu system

Samples within the Fe–Cu system with three different volume fractions of solid (50, 60 and 70 vol% Fe) and four different sintering times (2.5, 5, 17 and 66 min) were liquid phase sintered (LPS) in microgravity. Particle coarsening during LPS is generally known to increase with increasing volume fraction of solid. Contrary to expectations, there was an enhancement in particle coarsening with a decrease in the volume fraction of solid. The agglomerated microstructures observed in these samples (especially those with a lower volume fraction of solid) also exhibited a higher grain growth constant consistent with their higher 3D coordination number. The relevant analysis discussed in this paper strongly suggests that agglomeration is promoted by Brownian motion that dominates any density-driven force in the absence of gravity. The observed particle growth characteristics were in excellent agreement with the Lifshitz–Slyozov encounter modified theory, which incorporates the effect of higher solid volume fraction and particle coalescence into the LSW theory. The particle distributions appear to remain unchanged with processing time beyond 2.5 min, suggesting thereby, that agglomeration promotes an equilibrium particle configuration early on in the process and enables scaled grain growth with time.     

Experimental monitoring of the strengthening construction of a segmental box girder bridge and field testing of external prestressing tendons anchorage

Prestressed concrete segmental box girder bridges are composed of short concrete segments that are either precast or cast in situ and then joined together by longitudinally post-tensioning internal, external, or mixed tendons. The objectives of this study are to monitor the construction process of the external prestressing tendons to strengthen the bridge structure and perform a field load test to measure the strain and the deflection of the anchorage devices of the external prestressing tendons to determine the state of these devices after tension forces are applied. The monitoring process of the external prestressing tendons construction includes inspecting the cracks in the diaphragm anchorage and the deviation block devices before the tension forces are applied to the external tendons; measuring the deformation of the steel deviation cross beam during the tension process; measuring the deformation of the box girder after different levels of tension forces are applied; measuring the elongation of the external tendons in each level of the tension; and measuring the natural frequency of the external tendons after the tension process is complete. The results of the monitoring process show that the measured values of the deformation, the elongation, and the natural frequency meet the requirements. Therefore, there is no damage during the construction and the tensioning of the external prestressing tendons. A field load test is performed to the anchorage beam, the steel deviation block devices, and the steel deviation cross beam. The field load test results of the anchorage devices show that the values of the strains, the stresses, and the deflection are less than the respective allowable limit values in the requirements. Therefore, the anchorage devices have sufficient strength, and the working state is good after the tension forces are applied to the external prestressing tendons.     

Fungal assembly of L-asparaginase using solid-state fermentation: a review

Because of its antitumor therapeutic-activity, as well as its application in food industries to improve the quality, L-asparaginase has attracted considerable attention from several investigators. In recent years, fungi have occupied advanced rank among microorganisms in the production process of the enzyme. This review is spotting the light on the advantages of fungal enzyme and its applications in the food industry and medications. The solid-state fermentation was discussed as the wide alternative and most accepted biosynthesis technique. However, some lights were also spotted to the statistical experimental design of the fermentation process, mainly on the methodology of the response surface for L-asparaginase biosynthesis by fungi. Finally, the immobilization of the enzyme and the features of the widely used solid substrates for the maximization of the production process were explored.     

Effect of chemical composition and alumina content on structure and properties of ceramic insulators

In the present work, six electrical porcelain compositions with different amount of alumina and silica have been prepared and fired in an industrial furnace at 1300 °C. Density, porosity, bending strength and electrical strength were measured in the samples. In order to find a relationship between properties and sample microstructures, samples were analyzed by scanning electron microscope (SEM) and x-ray diffraction (XRD) techniques. The results showed that, with chemical composition of 53·5 wt.% SiO₂ and 37·5 wt.% alumina, highest electrical strength of 21·97 kV/mm was achieved in fabricated electrical porcelains. Increasing amount of alumina up to 30 wt.% decreases quartz and cristobalite phases, but increases corundum phase 3 to 5 times. SEM observation revealed that dense particles and uniform distribution of long and thin needle shaped mullite are predominant in sample microstructures with highest electrical strength.